INTRACELLULAR/TISSUE FLUID

Question 1

how are capillaries adapted? (3)

Answer 1

• thin permeable walls
• large sa for exchange
• blood flows slowly allowing time for exchange

Question 2

tissue fluid

Answer 2

• fluid from plasma forced through capillary walls

Question 3

what does tissue fluid do? (2)

Answer 3

• bathes cells, supplying them with solutes

- removes waste made by cell

Question 4

what is in tissue fluid?

Answer 4

glucose, a-acids, fatty acids, salts, hormones, o2

Question 5

what happens at the arterial end of a capillary bed? (5)

Answer 5

• blood under high pressure from heart/muscle contraction
• high hydrostatic pressure pushes liquid out from capillaries to spaces between the surrounding cells
• plasma pulls back water via osmosis (bc. low solute pot.)
• hydrostatic pressure is greater than plasma solute potential so solutes are forced out
• solutes are used in metabolic processes so are in higher conc, in the blood, so they diffuse from capillaries to tissues

Question 6

hydrostatic pressure

Answer 6

pressure exerted by fluid (in this case blood)

Question 7

what happens at the venous end of capillary bed? (4)

Answer 7

• hydrostatic pressure is lower because fluid has been lost
• plasma proteins are more conc. in blood because water loss
• so plasma solute pot. is much more negative and water potential is stronger than hydrostatic pressure and water is drawn back into the capillaries
• tissue fluid picks up waste (i.e co2) and diffuses down a concentration gradient from the cells to the capillaries

Question 8

What happens to fluid that doesn’t drain back into the capillaries? (2)

Answer 8

• drains into the lymphatic system

- returns to the venous system through the thoracic duct and empties into the left subclavian vein above the heart